The sealing of containers is often necessary for security reasons. Secure sealing of a container is of particular importance in case the container holds dangerous substances, such as for example fissile materials. It is further important to be able to easily identify the container and thereby its contents. Sealing devices are therefore often provided with identification elements. In an effort to increase security of the seal, such identification elements are often concealed and difficult to tamper with. As a result, such sealing devices can become rather expensive to produce. Furthermore, it is often difficult to verify if the sealing device has been correctly installed and if, and particularly when, it has been tampered with or broken. Depending on the contents of the container, it can be of great importance to be quickly informed of an illegal opening of the container.
It should be noted that the use of such sealing device is not limited to the shipment or storage of dangerous substances. There is also a need to use sealing devices on containers containing valuable cargo, such as e.g. electrical goods, cars, jewelry or even goods of personal value.
An example of a known sealing device is shown in patent application EP 1 063 627, which describes a sealing device with a housing and closure wire connected, when sealed, at both ends with the housing. The closure wire comprises two free ends which, when connected to the housing, establish an optical connection between a sender and a receiver connected to a microprocessor. When the closure wire is cut, the optical connection between sender and receiver is disrupted and the cutting of the closure wire is detected. The sealing device further comprises an infrared transmitter for transmitting status information to an external reader. In order to maintain the closure wire connected to the housing, a lock mechanism with a lock pin is suggested. The closure wire cannot be freed from the housing unless the lock pin is cut. However, if the lock pin and/or the closure wire are then replaced after an unauthorised access, such access may not be detectable.
There is hence a need to further improve the security of such sealing devices.